[PATCH v3] To make GIT-VERSION-FILE, search for git more widely

[Matthias Andree <matthias.andree@gmx.de>]

Situation: sudo make install rebuilds the whole package even if you've just
built it before. For instance:

make configure
./configure    # defaults to --prefix=/usr/local
make all doc
sudo make install install-doc install-html # REBUILDS HAPPEN HERE

This causes the "sudo make install" to rebuild everything because it believes
the version had changed.
sudo strips $PATH for security reasons.

The underlying problem flow is:

1 - Makefile has "include GIT-VERSION-FILE", thus gmake builds
    GIT-VERSION-FILE early.

2 - GIT-VERSION-FILE depends on a .PHONY target (.FORCE-GIT-VERSION-FILE)
3 - Thus, GNU make *always* executes GIT-VERSION-GEN
4 - GIT-VERSION-GEN now, under the stripped $PATH, cannot find "git" and
    sees a different version number.
5 - GIT-VERSION-GEN notes the difference in versions and regenerates
    GIT-VERSION-FILE, with up-to-date timestamp.
6 - GNU make rebuilds everything because GIT-VERSION-FILE is new.

The patch makes GIT-VERSION-GEN look for the current built git$X executable,
and in $(prefix)/bin/git, before falling back to plain "git" and thus to the
default version in GIT-VERSION-GEN.

Signed-off-by: Matthias Andree <matthias.andree@gmx.de>
---
 GIT-VERSION-GEN |    9 ++++-----
 Makefile        |    6 +++++-
 2 files changed, 9 insertions(+), 6 deletions(-)

diff --git a/GIT-VERSION-GEN b/GIT-VERSION-GEN
index 39cde78..d0dfef3 100755
--- a/GIT-VERSION-GEN
+++ b/GIT-VERSION-GEN
@@ -2,6 +2,7 @@
 
 GVF=GIT-VERSION-FILE
 DEF_VER=v1.6.3.GIT
+test -x "$GIT" || GIT=git
 
 LF='
 '
@@ -12,12 +13,12 @@ if test -f version
 then
 	VN=$(cat version) || VN="$DEF_VER"
 elif test -d .git -o -f .git &&
-	VN=$(git describe --abbrev=4 HEAD 2>/dev/null) &&
+	VN=$($GIT describe --abbrev=4 HEAD 2>/dev/null) &&
 	case "$VN" in
 	*$LF*) (exit 1) ;;
 	v[0-9]*)
-		git update-index -q --refresh
-		test -z "$(git diff-index --name-only HEAD --)" ||
+		$GIT update-index -q --refresh
+		test -z "$($GIT diff-index --name-only HEAD --)" ||
 		VN="$VN-dirty" ;;
 	esac
 then
@@ -38,5 +39,3 @@ test "$VN" = "$VC" || {
 	echo >&2 "GIT_VERSION = $VN"
 	echo "GIT_VERSION = $VN" >$GVF
 }
-
-
diff --git a/Makefile b/Makefile
index 6e21643..d6be483 100644
--- a/Makefile
+++ b/Makefile
@@ -177,7 +177,11 @@ all::
 # away (some NTFS drivers seem to zero the contents in that scenario).
 
 GIT-VERSION-FILE: .FORCE-GIT-VERSION-FILE
-	@$(SHELL_PATH) ./GIT-VERSION-GEN
+	@{ GIT=./git$X ; test -x "$$GIT" ; } \
+	    || { GIT=$(prefix)/bin/git$X ; test -x "$$GIT" ; }\
+	    || GIT=git ; \
+	    export GIT ; \
+	    $(SHELL_PATH) ./GIT-VERSION-GEN
 -include GIT-VERSION-FILE
 
 uname_S := $(shell sh -c 'uname -s 2>/dev/null || echo not')
-- 
1.6.3.1.geabc3